How Shoemakers Apply a Rubber Sole
When shoemakers apply a sole to a shoe upper they call it “bottoming.” Rubber is the most common material for shoe soles. It began competing with leather as a soling material in the 1930s. By the 21st century, thermoplastic or ethylene-propylene rubbers had been developed to be five or six times as durable as leather for shoe soles. Machining for shoe manufacture and adhesive technology have progressed alongside the advancements in rubber. The shoemaker’s task is to ensure that the correct adhesive matches the rubber material of the sole.
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Things You'll Need
- Shoemaker’s last – a mold that shapes the shoe upper
- Shoe uppers
- Rubber soles
- Wire brush
- Bristle cement/ adhesive brushes
- Chlorinated rubber primer
- Polychloroprene adhesive
- Polyurethane adhesive with hardener
- MEK (methyl ethyl ketone) solvent
- Cloths
- Infrared lamp or quartz halogen lamp
- Soling machine
- Bevel knife
- Nitrile rubber gloves
Instructions
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1
Fit the shoe upper on the shoemaker’s last. Scour or rough lightly the underside of the shoe’s upper material with the wire brush if it is a leather, resin or polyurethane finish. Wipe the underside with the MEK solvent if it is a PVC material.
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2
Scour the upper side of a micro cellular rubber sole with the wire brush. Wipe thermoplastic or polyurethane soles with the chlorinated rubber primer.
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3
Apply two coats of polychloroprene adhesive with the cement brush on the underside of the leather upper, allowing for an interval of between 10 and 15 minutes between each coat. Apply one coat of the same adhesive on the upper side of all rubber soles except PVC. Leave all surfaces to dry for 15 minutes. Align the sole and the upper and press in the soling machine at 4.0 to 5.5 bars for 15 to 20 minutes.
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4
Wipe the upper surface of a PVC sole with MEK solvent and apply polyurethane adhesive mixed with 7 percent to 10 percent hardener. Apply two coats of this adhesive to the underside of a leather upper and allow 15 minutes drying time between coats. Dry both surfaces for 15 to 20 minutes under an infrared or quartz halogen lamp. Align the sole with the upper and press in the soling machine at the same pressure as Step 3 for the same period while hot.
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5
Smooth and finish the edge of the complete shoe and sole with the beveling knife if necessary.
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1
Tips & Warnings
Shoe uppers made of natural textiles do not require scouring before adhesive application.
Make sure that the adhesives are well stirred before application.
Ensure all adhesive containers are kept airtight after use.
Make sure the work room is well ventilated and has an exhaust fan to remove solvent vapor.
Use nitrile rubber gloves when wiping with the chlorine-based solvent. The solution is damaging to skin.
References
Resources
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